With the rapid development of Internet and the popularization of large-screen multi-functional mobile phones, there appear a large number of mobile data multimedia services and various high bandwidth multimedia services, such as video conference, TV broadcast, video on demand, video advertisement, online education, interactive game, which not only meets the increasing service demand of the mobile user but also brings new service increase points to the mobile operators. These mobile data multimedia services require that a plurality of users can simultaneously receive the same data, and as compared to common data service, it has features such as large data amount, long duration, and sensitive delay. In order to effectively use the mobile network resources, the 3rd Generation Partnership Project (abbreviated as 3GPP) proposes MBMS, which is a technology for transmitting data from one data source to a plurality of targets, achieving the share of the network (including core network and access network) resources and improving the utilization rate of the network resources (especially air interface resources). The MBMS defined by 3GPP can not only achieve message class multicast and broadcast with pure text and low rate but also achieve the broadcast and multicast of high speed multimedia services and provide various rich video, audio and multimedia services, which undoubtedly conforms to the development trend of the future mobile data and provides a better service prospect for the development of 3G (3rd Generation).
In the LTE, the transmission of MBMS is done in a multi-cell mode to transmit, i.e. the MBMS sent by adjacent cells support combination. The essence of the combination is that several cells constitute an MBSFN area, then the cells constituting the MBSFN area send the same MBMS data on the same resources at the same moment, so that when the MBMS data sent by each cell are transmitted in the air, the data signals from different cells overlap with each other naturally in the air, thus increasing the reliability of the data, and the particular data transmission in the multi-cell mode can be made with reference to the description of Multi-cell transmission in Article 15, Section 3.3 of 36.300v920 protocol in the LTE protocol.
Currently, Multicast Traffic Channel (abbreviated as MTCH), Multicast Control Channel (abbreviated as MCCH), dynamic scheduling information (abbreviated as DSI, it is also referred to as MCH scheduling information, abbreviated as MSI) are formulated in the LTE, these information are all sent in the multi-cell mode, i.e. adjacent cells send the same above channel data on the same resources at the same moment so as to form an MBSFN combination area, even out of the MBSFN area boundary, information such as MTCH, MCCH, and DSI can also be normally received at the cell boundary, thus achieving the reception of MBMS. Currently in the LTE, the location of the MBSFN area is preconfigured that which cells belong which MBSFN area are fixed during networking, if the UE moves out of the MBSFN area, then he will not be able to normally receive the MBMS of this MBSFN area, that is to say, the MBSFN area is no longer consecutive, therefore, the MBMS in this MBSFN area is no longer consecutive, and so, the consecutiveness of the MBSFN area and the consecutiveness of the MBMS service in the MBSFN area is complementary. As such, when the user moves, the following situation may occur.
Due to the transmission feature of the MBMS in the LTE, the user can still normally receive the MBMS within a relatively large range after the user has moved out of the MBSFN area, which is because the control information about the MBMS is all sent in the manner of MBSFN and has rather strong signal overlap gain so that the control information still can be normally received by the UE when the UE has just moved out of the MBSFN area. For example, after the UE has just moved out of the MBSFN area, since the MCCH, MTCH and DSI information are all transmitted in the manner of MBSFN and have rather strong overlap gain, as long as the configuration information about the location of the MCCH channel in the SIB13 of the cell in the MBSFN area is not changed (which is the same as the case when UE moves out of the MBSFN area, in addition, according to the provisions of the LTE protocol, the location information about the MCCH channel on SIB13 is configured semi-statically and does not change for a long time), the UE can normally receive the MBMS within a relatively large range after having just moved out of the MBSFN area. However, at this moment, the UE has already actually moved out of the MBMS service area which subscribes with the operator, the operator cannot ensure the quality of the MBMS, and the MBMS may be accidentally interrupted.
As shown in FIG. 1, the areas surrounded by the curves constitute an MBSFN area ID1 area, in which cell B is a cell adjacent to the MBSFN area ID1 area, there is no MBMS in cell B or in other words, there is no service of the MBSFN area ID1 area, that is because there can be services of other MBSFN areas in cell B. Then, when a UE (User Equipment) which is receiving the MBMS moves from cell A to cell B, this UE can continue to receive the MBMS which is being received and belongs to the MBSFN area ID1 area at the moment when this UE just moves into cell B (i.e. the UE is still at the boundary of cell B close to cell A). This is because the MBMS data carried in MTCH and the control information MCCH and DSI of MBMS are all transmitted in the manner of multi-cell, after the same MBMS data from cells A, C and D naturally overlap with each other in the air, they can be normally received at a location in cell B close to MBSFN area ID1. However, with the UE continuing to move to the central area of cell B or a location farther away from the MBSFN area ID1, the reception effect of MBMS will become worse, until the MBMS cannot be received correctly, which causes the MBMS of this UE interrupted.
As to FIG. 2, the illustrated cell B belongs to a reserved cell in the MBSFN area ID1 area (the definition of reserved cell is described in Article 15 “MBSFN Area Reserved Cell” of 36.300 protocol), when the UE moves from cell A to reserved cell B, there also exist the above problems.
As to the user of this UE, the accident interruption of the MBMS makes the user feel bad, in case of no prompt information, the user does not know the MBMS signal becomes worse or the MBMS is stopped by the operator, thus making the quality of service evaluation to the operator by the user quite poor.